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Flashing
The following was taken from the m44 wiki and modified (Pin B36 is pin B5 on m43): There are two possible ways to flash the ECU, in the car and on the bench. In order to flash the ECU you must put battery voltage on pin B8 on the ECU. Having pin B8 at battery voltage when the ECU is turned on causes the ECU to enter bootloader mode, which allows the contents of the flash chip to be erased and written to. Flashing in the car is theoretically the easiest method to flash the ECU since no custom wiring is needed, however it is hard to maintain battery voltage above 13.5V. If have a powerful battery charger try the flash in car method first. To flash on the bench: Step 1:'You NEED at least a 13.5V source to flash properly. I used 14V, but anything up to 16.8V will work. '''Step 2:'Plugin your VAGCOM Cable into your PC. Hook jumper wires to pins 4(ground),7(k-line),16(+13.5v). See picture below for pin-outs. 'Step 3:'Hook up jumper wires to your ECU like the following. Connect power(+14V) to pins A12,A26,A27 on the ECU. Connect a ground to either A13,A18,A28,A42, all ground pins are tied together so only one connection is needed. Connect +13.5V to pin B8 on the ECU, this is the bootmode pin and will allow the ECU to go into programming mode. Then connect pin 7 of the VAGCOM to pin B5 on the ECU. The ECU must share the same ground and power as the VAG-COM cable! '''Step 4: '''Open up the Motronic 4X flashing utility in tuner pro. Select your binary to flash and click flash, wait for the process to complete. If you have trouble getting your ECU to flash you may need to change some serial settings. Go to Device Manger, Ports (COM), right click on your VAGCOM, click on properties, then go to port settings, advance and set latency timer to 25ms. To flash in the car: # You must figure out a way to engage bootloader mode while the ECU is in the car; you must get pin B8 to battery voltage. There are a few methods of doing this, open the ECU box and wire a switch between pins B8 and A12(ignition power). Or you can solder a long wire to pin B8 and run it to the positive post on your battery. Also you must find a similar way to connect pin B5 to pin 7 of the vagcom. # Connect a battery charger, turn the key to position II and check the battery voltage, if it is above 13.5 you can flash. If the voltage is too low it can help to disconnect the ground wire for the radiator cooling fan, (the fan will run if the ECU is turned on while in bootloader more), and turn off interior lights, radio, and climate control. If you need to raise voltage more, try taking out the fuel pump fuse and other accesory fuses. When flashing has completed, turn key off, disconnect power from pin B8. '''Remember toreconnect Cooling Fan, or you will overheat!